In the field of metal finishing there is a need for decorative or quasi-decorative metallic finishes which are sacrificially anodic with respect to a metal being protected. The classic, sacrificially anodic, coating metal is zinc used extensively in galvanized coatings. It is desirable to provide a sacrificially anodic coating metal which has enhanced corrosion resistance compared to zinc.
Electrodeposited nickel-zinc alloy coatings have been suggested for corrosion protection purposes, for example, in the documents abstracted in Chemical Abstracts listed as follows:
69 CA 56463v PA1 78 CA 66117k PA1 T. L. Rama Char, Proc. Australian Conf. Electrochem, 1st, Sydney, Hobart, Australia 1963, 384-91. PA1 S. Sathyanarayana and T. L. Rama Char, Bull. India Sect. Electrochem. Soc. 5 (4), 83-85 (1956). PA1 A. Brenner, Electrodeposition of Alloys Academic Press, New York, 1963, v. 2, p 216. PA1 J. Dini and H. Johnson, presented at the Government-Industry Workshop on Alternatives for Cadmium Electroplating in Metal Finishing, Oct. 4-6, 1977. PA1 S. Venkatachalam, Some Peculiar Observations in the Electrodeposition of Nickel-Zinc Alloys from the Sulphamate Bath, Bull. Indian Section, Electrochem. Soc. 10, 93 (1961).
The use of an electrodeposited nickel-zinc alloy layer as a part of a plated system involving a corrodible basis metal having successive deposits of zinc-nickel alloy, nickel and chromium is disclosed in U.S. Pat. No. 3,691,027. Other disclosures known to us relative to nickel-zinc plating are as follows:
The present invention is directed to novel plating baths and plating procedures for producing decorative quality or quasi-decorative quality nickel-zinc alloy deposits useful for purposes envisioned by the prior art and for other uses.